Both players have been on trial with the club throughout pre-season but have now officially signed ahead of the new season.
Keane is a central defender that has previously played for Derby County, Alfreton Town, Exeter City, Eastwood Town, Carlton Town and Long Eaton.
The 25-year-old brings great experience that could be vital for the Nailers defence despite still being a rather young player.
Barr-Rostron re-joins the Nailers after his loan spell with the club in 2015 from Lincoln City.
The 20-year-old played for the Imps youth side before loans to Brigg Town as well as Belper. He moved on from Lincoln City in at the beginning of last season before moving to Boston United.
The Nailers are happy to add these two important players to their squad and look forward to seeing them in action through the season.